[riscv-port-jdk11u:riscv-port] RFR: 8337780: RISC-V: C2: Change C calling convention for sp to NS

[Gui Cao]

On Sun, 25 Aug 2024 14:36:24 GMT, Gui Cao <gcao at openjdk.org> wrote:

> Hi, Please help review this backport to riscv-port-jdk11u.
> Clean backport of JDK-8337780 to reduce frame size by 16 bytes and improve performance for some C2 runtime stubs as we do not have to save sp on the method entry.
> 
> ### Testing
> - [x] Run tier1-3 tests on SOPHON SG2042 (release)

Thanks for the review.

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PR Comment: https://git.openjdk.org/riscv-port-jdk11u/pull/26#issuecomment-2325416240